1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device including, for example, a plurality of semiconductor chips which are bonded to each other, particularly, to an improvement of bonding of semiconductor chips used in a high density mounting.
2. Description of the Related Art
A semiconductor device including a plurality of semiconductor chips adapted for a high density mounting and bonded to each other in a three dimensional direction is proposed in, for example, Japanese Patent Disclosure (Kokai) No. 60-241228. In this prior art, each semiconductor chip is provided with, for example, a solder bump not only on the upper surface but also on the side and lower surfaces so as to enable a plurality of chips to be bonded to each other in a three dimensional direction. However, since the solder bump is generally spherical, the adjacent chips are brought into a point-to-point contact with each other via the bump. This makes it difficult to have the chips easily and accurately aligned to each other with the result that the semiconductor device is rendered unsatisfactory in the bonding strength between adjacent chips and in the reliability of electric connection.